Antiperspirant and deodorant products are well-known in the cosmetic art. They are generally used by rubbing an area of the body such as the underarm to apply a layer of the composition to the skin which reduces odor and/or perspiration. It is desirable that such products have aesthetic characteristics of non-crumbling, smoothness, non-oiliness and non-tackiness. Clarity of such products is a long-sought desirable aesthetic characteristic. Another desirable characteristic is that no readily visible residue as, e.g., a white layer, be left on the skin after the deodorant or antiperspirant is applied.
Antiperspirant and deodorant products have appeared in the marketplace in various dosage forms, such as sticks, gels, roll-ons, aerosols and creams. Generally, these dosage forms include a solution of the active ingredient in a suitable solvent, a suspension of the active ingredient in a non-solvent, or a multiphase dispersion or emulsion in which a solution of the active ingredient is dispersed in some continuous phase or in which the solubilized active ingredient constitutes the continuous phase.
The stick form has become the dominant antiperspirant dosage form in the United States market, constituting more than 50% of total antiperspirant sales, and is popular to varying degrees globally. Cosmetically acceptable antiperspirant sticks typically consist of a suspension of spray-dried active antiperspirant material in vehicles such as cyclomethicone, with a waxy substance such as stearyl alcohol, alone or in combination with castor wax, gelling or thickening the suspension sufficiently to create a suitable stick.
The stick form can be distinguished from a gel or a paste in that in a stick, the formulated product can maintain its shape for extended time periods outside the package, the product not losing its shape significantly (allowing for some shrinkage due to solvent evaporation).
The hard stick dosage form, although widely accepted by the consumer, suffers from leaving a white residue on skin after application, and can cause staining of fabric, which is considered to be undesirable, particularly by female consumers. The gel dosage form can be formulated to reduce and/or eliminate the white residue.
One such clear gel antiperspirant is set forth in International Patent Application No. WO 92/05767, published on Apr. 16, 1992 (The Gillette Company), which is incorporated herein by reference. This patent application pertains generally to a clear gel-type cosmetic product which includes an emulsion with an oil phase and a water phase that includes an incorporated active ingredient. The oil phase preferably makes up about 10 to 25% of the product and includes an emulsifier which when properly mixed with the water phase components yields a water-in-oil emulsion. The oil phase is typically a blend of liquids and includes a polyorganosiloxane (e.g., dimethicone) and a silicone emulsifying agent. A particularly suitable emulsifying agent is a polyether substituted silicone of cyclomethicone and dimethicone copolyol. This emulsifier is useful for preparing stable water-in-oil silicone emulsions where silicone makes up a large portion of the oil phase, and is a dispersion of a silicone surfactant (i.e., dimethicone copolyol), i.e., 10% silicone surfactant in cyclomethicone (i.e., a silicone solvent). The water phase includes one or more polar species such as water, propylene glycol, sorbitol and ethanol. The water phase includes, in solution, a deodorant and/or antiperspirant active ingredient such a triclosan, benzethonium chloride and/or an astringent salt of aluminum or zirconium, such as aluminum chlorohydrate or aluminum zirconium tetrachlorohydrex-glycine. The gel can also contain additional cosmetic ingredients such as emollients, colorants, fragrances, and preservatives.
It has been unexpectedly discovered that ester functionalized silicones of the present disclosure raises and improves the refractive index (RI) of the silicone significantly, which provides great benefit in personal care applications. That is, such formulations will show benefit as antiwhitening agents in antiperspirants and sunscreens.
These unique ester functionalized silicones maintain the same great surface tension property of silicone, i.e., provide the same spreading and silky feel as silicone in personal care formulations.
In addition to the two properties mentioned above, the silicone esters of the present disclosure provide enhanced formulation flexibility and provide ease to integrate various components that are not mixable otherwise.
Some examples of conventional gel antiperspirants and deodorants are set forth below:
Antiperspirant Water Phase Water 37.01% Aluminum Chlorohydrate 30.00% Ethanol 10.00% Propylene Glycol 4.99% Oil Phase Dimethicone 9.85% Cyclomethicone & Dimethicone Copolyol 8.00% Fragrance 0.15% Deodorant Water Phase Water 33.25% Sorbitol 14.00% Ethanol 12.00% Propylene Glycol 22.50% Triclosan 0.25% Sodium Hydroxide 0.02% Oil Phase Dimethicone 9.70% Cyclomethicone & Dimethicone Copolyol 8.00% Fragrance 0.30%.
International Patent Application No. WO 97/06777, which is incorporated herein by reference, also discloses a clear cosmetic gel composition which includes: (1) an aqueous phase containing water and at least one cosmetically active ingredient, (2) an oil phase containing a high refractive index material, (3) at least one coupling agent to bring the aqueous phase and the oil phase into a homogeneous composition, and (4) an alkoxylated, alkyl substituted siloxane surface active agent in an amount sufficient to form the composition into a water-in-oil emulsion. The oil phase includes a volatile silicone fluid, a non-volatile silicone fluid and an emollient. The emollient is preferably phenyl trimethicone.
U.S. Pat. No. 4,900,542 (Parrotta, Jr., et al.), which issued on Feb. 13, 1990 and which is incorporated herein by reference, discloses a process for preparing uniform, clear, microcrystalline emulsion antiperspirant compositions of gel-like consistency comprising: mixing the antiperspirant active material with water, charging the aqueous phase into an oil-alcohol phase containing a volatile silicone, a silicone emulsifier, a non-volatile emollient and a coupling agent, heating the resultant mixture with agitation until a uniform mixture is obtained, homogenizing the mixture and passing the homogenized mixture to a holding tank or directly to a filter.
The clear gel antiperspirants and deodorants described above are based on water-in-oil emulsions which are stabilized with a silicone surfactant. The silicone surfactant is commercially available as a 10 wt. % solution in a volatile silicone solvent, such as cyclomethicone (also known as decamethycyclopentasiloxane and/or octamethylcyclotetrasiloxane).
Esters have been used for a number of years for a variety of personal care applications including solids dispersion. The esters are fully esterified, i.e., for esters of polyhydric alcohols, nearly all the hydroxyl groups have been reacted with acids so that the hydroxyl number is generally less than about 5.
Zinc oxides have been used in the cosmetics industry as a potent sunscreen in concentrations in the range between 2 to 10% usually in oil-in-water formulations. To be effective it must be well dispersed to coat the skin evenly to prevent harmful ultraviolet (UV) rays from reaching the skin surface. If not dispersed effectively agglomeration occurs resulting in uneven distribution over the skin surface resulting in UV penetration of gaps in the surface layering.
The present inventors have discovered that utilization of a silicone based fluid made with partially esterified esters as a dispersing agent provides desired branching and reactive intermediates to effectively disperse inorganic solids, such as zinc oxide, thereby reducing the amount of zinc oxide required for use in personal care applications, such as sunscreens and color cosmetics.